44,176 research outputs found

    Health impacts of wind turbines

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    This report presents the results of a rapid, desk based analysis of peer reviewed UK and international literature from the last four years on the effects of wind turbines on human health. The review covers literature specified by the Scottish government, peer-reviewed original studies and recent peer-reviewed literature reviews. Recent original studies consist mostly of cross-sectional studies and case studies on the effects of wind turbines on local residents. All studies present evidence for annoyance due to wind turbine noise and most concur that there is evidence for sleep disturbance in the presence of wind farms but not necessarily from noise. Both results are in agreement with the effects of noise from other environmental sources. Other health effects are increasingly reported in the presence of wind turbines but the reviewed literature does not provide firm scientific evidence of a causal relationship with wind turbines or even more specifically wind turbine noise. The most widely quoted cross-sectional studies show correlations between annoyance and visual impact, economic benefit and attitude related to wind turbines. Wind turbine sound is reported to be comparatively weakly related to annoyance and inseparable from the other contributing factors. Literature on low frequency noise and infrasound (LFIS) can be categorised as reviews, sound level measurements around windfarms and discussion of mechanisms of perception and response. A Swedish review finds no evidence to support ‘wind turbine syndrome’ while another concludes that further research is required. Regarding noise measurements, there are concerns that a new generation of wind turbines will produce a sound with a spectrum shifted down in frequency. However, a study in Australia concluded that infrasound levels near windfarms were no higher than elsewhere and that higher levels in urban areas were probably due to traffic and other human activity rather than wind turbines. Some other studies found measured sound levels near wind farms to conform with a range of criteria for LFIS. Papers by Salt et al. propose that LFIS may differentially stimulate structures in the human inner ear, and may instigate health effects even when inaudible. The authors seek to build a speculative case utilising experimental data gleaned from guinea pigs and some observations on human experiences with specific pathological conditions. Based upon the documents submitted, the proposal is unproven, and would need clear data from hypothesis driven independent research in humans in order to be credible. A proposal by US consultants that motion sickness-like symptoms reported at one wind farm might be caused by acoustic excitation of the balance organs is not new and has previously been discounted as an explanation for similar reported effects not involving wind turbines. Other evidence on acoustic stimulation of the balance organs has been noted but not reviewed. Health effects from other wind turbine related sources such as shadow flicker have been reported in several studies and guidelines to be less of a problem. Careful wind farm design and operational restrictions are suggested to be sufficient to minimise the impact. The mitigation strategies have been found to vary widely internationally with some countries and federal states using fixed noise limits, others using noise limits relative to existing background levels and many like the UK using a combination of both. Set-back distances are also used internationally but have a number of disadvantages. The relevant UK guideline document ETSU-R-97 aims to provide a reasonable degree of protection to noise sensitive listeners; without unduly restricting the development of wind turbine renewable energy resources. In the international comparison the ETSU-R-97 guidelines tends to result in comparatively low noise limits although direct comparisons between fixed and relative noise limits are difficult. ETSU-R-97 has been criticised for its inconsistent implementation and relative complexity. Good practice guidelines by the Institute of Acoustics which aim to address the implementation issues are due to be published in May

    Habitat width along a latitudinal gradient

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    We use the Chowdhury ecosystem model, one of the most complex agent-based ecological models, to test the latitude-niche breadth hypothesis, with regard to habitat width, i.e., whether tropical species generally have narrower habitats than high latitude ones. Application of the model has given realistic results in previous studies on latitudinal gradients in species diversity and Rapoport's rule. Here we show that tropical species with sufficient vagility and time to spread into adjacent habitats, tend to have wider habitats than high latitude ones, contradicting the latitude-niche breadth hypothesis.Comment: 13 pages including all figures, draft for a biology journa

    The viscosity radius in dilute polymer solutions: Universal behaviour from DNA rheology and Brownian dynamics simulations

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    The swelling of the viscosity radius, αη\alpha_\eta, and the universal viscosity ratio, UηRU_{\eta R}, have been determined experimentally for linear DNA molecules in dilute solutions with excess salt, and numerically by Brownian dynamics simulations, as a function of the solvent quality. In the latter instance, asymptotic parameter free predictions have been obtained by extrapolating simulation data for finite chains to the long chain limit. Experiments and simulations show a universal crossover for αη\alpha_\eta and UηRU_{\eta R} from θ\theta to good solvents in line with earlier observations on synthetic polymer-solvent systems. The significant difference between the swelling of the dynamic viscosity radius from the observed swelling of the static radius of gyration, is shown to arise from the presence of hydrodynamic interactions in the non-draining limit. Simulated values of αη\alpha_\eta and UηRU_{\eta R} are in good agreement with experimental measurements in synthetic polymer solutions reported previously, and with the measurements in linear DNA solutions reported here.Comment: 19 pages, 14 figures, two column, Supporting Information added, to appear in Macromolecule

    Swift J164449.3+573451 event: generation in the collapsing star cluster?

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    We discuss the multiband energy release in a model of a collapsing galactic nucleus, and we try to interpret the unique super-long cosmic gamma-ray event Swift J164449.3+573451 (GRB 110328A by early classification) in this scenario. Neutron stars and stellar-mass black holes can form evolutionary a compact self-gravitating subsystem in the galactic center. Collisions and merges of these stellar remnants during an avalanche contraction and collapse of the cluster core can produce powerful events in different bands due to several mechanisms. Collisions of neutron stars and stellar-mass black holes can generate gamma-ray bursts (GRBs) similar to the ordinary models of short GRB origin. The bright peaks during the first two days may also be a consequence of multiple matter supply (due to matter release in the collisions) and accretion onto the forming supermassive black hole. Numerous smaller peaks and later quasi-steady radiation can arise from gravitational lensing, late accretion of gas onto the supermassive black hole, and from particle acceleration by shock waves. Even if this model will not reproduce exactly all the Swift J164449.3+573451 properties in future observations, such collapses of galactic nuclei can be available for detection in other events.Comment: 7 pages, replaced by the final versio

    Monte Carlo Simulation of the Three-dimensional Ising Spin Glass

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    We study the 3D Edwards-Anderson model with binary interactions by Monte Carlo simulations. Direct evidence of finite-size scaling is provided, and the universal finite-size scaling functions are determined. Using an iterative extrapolation procedure, Monte Carlo data are extrapolated to infinite volume up to correlation length \xi = 140. The infinite volume data are consistent with both a continuous phase transition at finite temperature and an essential singularity at finite temperature. An essential singularity at zero temperature is excluded.Comment: 5 pages, 6 figures. Proceedings of the Workshop "Computer Simulation Studies in Condensed Matter Physics XII", Eds. D.P. Landau, S.P. Lewis, and H.B. Schuettler, (Springer Verlag, Heidelberg, Berlin, 1999

    Targeted In Vivo Electroporation Using Nanoengineered Microelectrodes

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    Targeted electroporation by using glass microelectrodes is a popular and versatile tool allowing for easy manipulation of single cells and cell ensembles in living tissue. Because of the highly focal distribution of the electric field, however, the range of reversible electroporation without causing irreversible damage is tight-especially when aiming for larger electroporation volumes. In this chapter, we describe the production of nanoengineered electroporation microelectrodes (NEMs), a practicable way to prepare glass microelectrodes providing a more even distribution around the tip of a pipette by using nanotechnological methods

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